Target zones of the project

Sahel 

Global warming is having a profound impact on the water cycle in sub-Saharan Africa, particularly in the Sahel, affecting all its components (rainfall, runoff, groundwater recharge) at all scales that matter for human activity. A recent example of these deep-seated changes is the evidence of a continuous increase in the proportion of annual rainfall generated by intense rainfall in this region, even though the occurrence of rainfall continues to be deficient compared to what it was during the two wet decades 1950-1970.

The most immediate consequences of these hydro-climatic changes are, on the one hand, a sharp increase in deadly floods and, on the other hand, the maintenance of a strong hazard on agricultural yields, even in a generally favorable year, as we saw in 2020 in Niger with pockets of drought and poor harvests. Floods and food shortages are as many shocks in the Sahel, generating population displacements that can turn into more distant and permanent migrations when they occur at short intervals.

As the population increases, so does the need for energy and food, as well as vulnerability to floods and droughts. The potential of water resources is still very important: for hydroelectric production on many equatorial rivers, including the Congo, and for food production in the Senegal and Niger basins in particular. But in the current context, a better knowledge of the resources in this region becomes critical both to optimize their mobilization and their distribution between these uses, and to protect populations from climate risks.

Niger River Basin :

The Niger River Basin, the 4th largest basin in Africa, covers an area of 2.2 million km2 and nine countries in West Africa: Algeria, Benin, Burkina Faso, Cameroon, Chad, Guinea, Ivory Coast, Mali, Niger and Nigeria. This basin is particularly vulnerable to climate change. The river and its tributaries are subject to concerted management by the Niger Basin Authority, which brings together the nine riparian states of the river. This river is of significant importance for many economic and agricultural activities, for drinking water supply and hydroelectricity production: it is therefore the subject of much research, particularly on the evolution of water resources, the river’s floods and its development. The sustained drop in rainfall throughout the Sahelian region since 1970 has led to changes in the river’s regime throughout its course (drop in water table levels in humid regions, intensification of flow coefficients in Sahelian regions). 

Niamey (Niger) : 

The city of Niamey, capital of Niger, with a population of 1.8 million, is located on the Niger River. For several years now, the city has been affected by destructive annual floods. These floods usually occur during the rainy season (June – September), particularly in August, when the rains are heavy and not far apart. In parallel, the city also suffers from flooding in the dry season, related to the flooding of the river, usually during the months of December and January. 

In 2020, the city was affected by heavy rains, and several areas of the capital were engulfed by water. These rains resulted in nearly 50,000 people being affected (MAH/GC figures) and many households losing their homes, crops and livestock. 

 

Senegal River Valley : 

The Senegal River extends over 1750 km and crosses Mali, Mauritania and Senegal. Its basin covers about 337,000 km2 and extends beyond the three countries of the river to Guinea. The Senegal River regime is irregular and depends on monsoon rains, the basin is in fact in a semi-arid climatic zone, with irregular rainfall. In 1972, the riparian States of the River created the OMVS (Organization for the Development of the Senegal River) aiming to develop the river and exploit its resources rationally, within the framework of IWRM. 

 

 Dakar (Senegal) :

The city of Dakar is the capital of the Republic of Senegal, with a population of over 3 million. Dakar has grown very rapidly, from 400,000 inhabitants in 1970 to more than 3 million in 2018, due to migration from the countryside and natural increase. The city is regularly affected by heavy flooding during the annual rainy season, causing significant damage to public infrastructure and threatening the health of the population, especially the poorest. 

Andes :

As observed in West Africa, an intensification of the hydrological regime has been documented in tropical South America. In the Amazon basin, the frequency of extreme floods has increased from 1/20 years before the 1970s to 1/4 years after the 1990s. This intensification is particularly noticeable in the northwestern part of the basin, especially in the Andean-Amazonian region of Colombia, Ecuador and the northern Peruvian Amazon. These floods have strongly impacted the populations, in the Amazon and in the Andean foothills, for example in Mocoa (Colombia) in 2017 or in Cuzco (Peru) in 2010, among others.

Since the beginning of the 21st century, an increase in moisture fluxes from the Atlantic and Caribbean Sea has been observed, modifying the main climatic mechanisms associated with the interannual variability of precipitation in the Central Andes and the Peruvian-Bolivian Altiplano. This change makes more complicated the operational prediction of extreme climatic events and their future projection in the framework of climate change.

On the other hand, in the south of the Amazon Basin, the dry season is getting longer and rainfall and river flows are decreasing. Global warming, on the one hand, and the degradation of the Amazon forest, on the other, are a real threat to the food and energy security of the Andean countries.

A number of the watersheds most threatened by future changes span several Andean countries. Therefore, developing an integrated vision of hydroclimatic trajectories in this region is a necessity for decision makers and managers. From an operational point of view, the prediction and management of hydroclimatic risks is also a challenge in this regional context.

Lake Titicaca : 


Lake Titicaca is located in the Andes Mountains, at 3,812 meters above sea level, and covers approximately 8,562 km2, of which 4,772 km2 (56%) correspond to Peruvian territory and the rest (3,790 km2, or 44%) to Bolivia. It is the biggest lake of South America in terms of volume of water and length (190 km). It is in the center of a large basin with an area of about 58,000 km2, of which 39,017 km2 is in Peru, belonging to more than 80% of the Peruvian territory. The watershed is subdivided into ten sub-basins. More than twenty-five rivers flow into Lake Titicaca and it has 41 islands, some of which are inhabited.

Lake Titicaca is filled with water from rainfall runoff and snowmelt. Since September 11, 1998, it is classified as a Ramsar site for the importance of its wetlands.

 

Upper Beni Basin : 

The Río Beni is a river in western Bolivia that joins the Río Mamoré to form the Río Madeira, the main tributary of the Amazon. Its basin covers an area of over 283,000 km2 (including the basins of all its tributaries). It extends in Bolivia and Peru.

The Beni is born on the eastern slope of the Andes from the junction of multiple rivers that descend from the mountain.

The upper basin of the Beni is complex because it is made up of a range of comparable rivers that change name at each important confluence. In addition, rainfall and runoff are very heterogeneous between the relatively dry high Andean valleys (600 to 1000 mm of rain per year) and the mountain slopes (Yungas) which take the full brunt of the humidity that comes from the Amazon (4 to 6 meters of rain per year). As a result, the torrents that make up the upper course of the Beni grow considerably in a few dozen kilometers as they leave the mountain. The erosion is one of the most active in the Amazon basin.